Bascule-bridge.



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ysAscuLE BRIDGE. APPucATxoN msufoc. 28. 1915.

yPaftented Jan. 2, 1917.

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3 SHE ,L EQBROWN. BASCULE BRIDGE. APPLICATION lFILED DCT. 2B. 1915.

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/oooooi -Kooooo THOMAS E. BROWN, 0F NEW YORK, Y'.

BAscULn-BRIDGE.

Application ined october 2s, 1915` serial no. 53,324.

Togall 'whom t may concern:

Be it known that I, THOMAS E. BROWN, a citizen of the United States, anda resident of the borough of Manhattan, in ,-the county of New York and State of New York, have invented certain newand useful Improvements in'Bascule-Brid'ges, of which the following is a specification.

This invention' relates to improvements in bascule bridges, of the class which are balanced by counterweights and flexible counterweight connections, and wherein said connections are supported by curved members, and especially where saidv supports are curved in a manner to maintain the balance of the' bridge in all its positions.

In my vUnited States Letters Patent No.

1,151,657, August 31, 1915, I .have `shown and described a method of effecting the balance and operation of bascule bridges by means of counterweights and, flexible connections supported by curved members, and

the objects ofthis invention are to simplify and cheapen the construction of such curved` members and prov-idea 'form of construction in which the several parts of said.

curved members can be easily and accurately placed in position, and in which said positions can readily be determined by a simple graphic process, .and especially in which the construction of the bridge may proceedbefore said calculations are finally completed.l

' In bascule bridges the position and curvature' of the balancingdevices depend upon the position of the center of gravity of the moving portion of the bridge. An accurate determination of the position of the center of gravity can not be made until the shop drawings of the bridge are,completed, and in fact, in some cases, not until a considerable portion of the bridge structure has i lbeen completed; `and said position may be altered by addition of tracks, changes in iooring and other details even after thev bridge has been substantially completed.

It is therefore another important object of my invention to so'provde for the construction of the aforesaid curves by sectional elements that said curves need not befinally determined before the commencement of the construction of the bridge and readily be changed even after the erection of the bridge. Where flexible members are l Specication of Letters P atent.

'Fig 7 is a used for the connection ofthe counterweight to the bridge large sheave wheels are required to support saidconnections, and -said Patent-eu aan. 2, fait.

sheave `wheels are frequently ofI too large diameter to be turned inv ordinary lathes, and another object? of my invention is -a method of construction of suchv supporting wheels which avoids the necessity of turning their rims, and also enables the strength of their parts to be determined by the simple method used in the calculation of ordinary framed structures.

I prefer to use cables for the/counter weight connections, and hereinafter use thev word cable when referring to such a connection, although the` connection may be constructed of chains, link bars or other suitable devices. i l

Referring to the` drawings which accompany the specification jto aid the description, Figure 1 is -a side elevation of a bridge equipped with my counterbalancing device. Fig. 2 is a broken section of a portion of the bridge, onlarge scale, showing the method of constructing thecurves for effecting the balance of the bridge. Fig. 3 isa broken section on a'larger scale, on line of Fig. 2. Fig. 4 is a side view and Fig. 5 a plan view of a saddle,-on large scale. Fig. 6 shows -a'section 'of a leading sheave constructed on the same principle as the curve shown in Fig. 2, and on the same scale. broken section on the j scale of Fig. 8, .of the leading sheave rim showing a detail of its construction, and Fig, 8 is anedge view of a portion of the sheave rim showing the preferred arrangement of the spokes and saddles. f

It is to beunde'rstood that Figs. 1 and 2 show the counterbalancing devices for only one side of the bridge, but that generally, in

4practice, these devices will 'be duplicated, Vthere being one set of such-devices foreach side of the bridge; therefore, in the description of said figures which follows, reference is made to the devices on one side only, the

corresponding parts on the other sideof the bridge being similar to those described'. Re- A ferring to said Fig. 1, B -is a bascule bridge; A 'A being the piers; P the pivot4 about vwhich the bridge turns; T the tower; C the main counterweight cable; C the secondary counterweight cable;'S and S guide sheaves for said cables and C. on the top of the tower; Da winding drumfor said cable C,. and 1V and W counterweights respectively suspended on the cables C andC. i p

The letters 0 g.. represent the position of the center of gravity of the bridge.

TheA total weight of the two counterweights W' and lV is preferably just suiiicient to balance the bascule bridge when in its lowest position, and by rotatingsaicl4 drum by any suitable'power'in the proper direction lsaid bridge B may-be raised or lowered.

The secondary counterweight cable C is attached to some suitable point ofthe bridge, as the elbow .of the upper chord f, and said primary cable C passes around a curve F, (Figs. 1 and 2) and is fastened at somepoint of the bridge, preferably at the pivot P; said curveF forming a curved way or `rim supporting the said cable C. Said curved way or rim is secured preferably to the upper side of the bridge', as shown, lby suitable framing such as the post .and tie the pivot P to their cables C plusthe sec ondary weights WV multiplied by the perpendicular distances from saidA pivot 1) to their cables C must equal-the weight of the bridge multiplied by the horizontal distance from t-lie said pivot l) to the vertical yline t/hrough the center of gravity of the bridge; said perpendicular distances from the said pivot Pto the line of pull of the respective ,cables being their lever arms, or algebraically expressed wwwa/:Bv COS. a p in which W and WV represent the tota-l `weight of the respective counterweights, Z

and Z represent the lever arms of the re-. spective counterweight `cables around the pivot of the bridge, B represents the weight of the bridge, r V the radius from the pivot P to the center of gravity of the bridge, and os the angle which said radius malresiwith the horizontal.

The operation ofthe bridge is fully described in my aforesaid Letters Patent No.

1,151,657, and it is only necessary. herein to show the method of laying out the curves F and F.

Having found various values of the -lever arm of cable C, (which are represented by Z Ain said formula) for various positions of the bridge by means of the aforesaid for; mula, we describe arcs from pivot P as a cenvtively Fig. 1. vsheave about the pivot P into corresponding positions, as obviously the relative po-l ter,'with said values of Z as radii, See the l dotted arcsnumbered 1,2, 3, 4, etc., respe'c-v Ve then rotate the leading sitions of the bridge and the leading sheave S are the same whether we rotate the bridge about the pivot P in one direction, the ,I

sheave remaining fixed, or whether we rotate the sheave about the pivot P in the op-' posite direction, the bridge remaining fixed.

'Having rotated the sheave into its corresponding positions 2,` 3, 4, etc., as'indicated by the dotted sheaves in Fig. 1, we draw lines 1., 2, 3, 4, etc., tangent to both the shea-ve and arc of correspondingpositions, and the intersectingvportions of these vlines form a polygon consisting ofa series of tangents to therequired curve onthe-bridge, the closeness of'approach of said polygon to the Iactual culrvedepending on berof positions taken. I

The-,construction of a continuouscurve of continually varying radius of curvature is difficult and expensive, and I prefer to use,`

instead of a continuous curve, a plurality of short segments orsa'ddles'lO, as shown 1n Figs. 1 `and 2, each being of a radius less* than the radius of curvature of the true curve. Such segments may be easily fitted the numv to the tangents of the curve found las above described and their-positions can be accurately` determined on a large scale drawing, and also said segments may be easily and cheaply placed in their 'proper positions on the bridge.

Referring to Figs. 2 and, t and t are'the posts and tie as shown in Fig. 1. v-Each post is preferably ,made of wide plates 11 with angle iron flanges 12, said plates 11 being wide enough to containx the curve F with allowance for any variation in said curve F likely to be caused by possible changein .the position of the center of gravity *of the bridge as hereinbefore described, and 13 are similar plates for the reversed curve F. 10` are short segmental saddles preferably grooved to receive the parts 14 forming the cable C. Said segments 10, one of which is shown in side view in Fig. 4 and in plan View in Fig. 5, have flanges 15 which t betweensaidplates 11 and 13, and by which they may be bolted or preferably riveted to said plates 11 .and 13. Said segments 10 are 'l of a radius equal to or' shorter than the mini-l mum radius of curvature of the curves F and F, and when in place cause the cable C to lie in av series of short chords and arcs, so closely approximating the true continuous curve, that the error ,need not exceed onefifth of one per cent., a degree of accuracy closer than is actually needed in practice.

It will ybe readily understood, especially from Figs. 2 and 3, that the rivet holes need not be drilled and` the segments need not be y placed until the position of thecenter of gravity of the bridge has been finally determined and their correct positions found,

vand even if placed may readily be changed in position by cutting out rivets and drilling new holes, and the construction ofthe bridge therefore need not be delayed pendingeract determination of the center of gravity.

F igs 6, 7 and 8 show the preferredconstruction of the leading sheave S; Fig. 6 being a broken section in the central plane of 'the -sheave and Fig. 7 a section through the rim on a larger scale. The sheave Sis preferably built up.of structural shapes, and the rim preferably consists of plates 16 between which are riveted short segments or saddles 10 similar to the segments 10 before descri-bed for the curves F and F The segments 10 may be placed between the spokes 1T of the sheave S as shown on thev upper part of Fig. 6, or may if preferred be placed at the spokes 17 as shown on the lower broken part of Fig. 6.

' The saddles 10.are of a radius less than theradius of the sheave S and the cable lies 4on the saddles in a series of short 'chords and arcs. By using a suita-bletemplet for drilling the rivet holes inthe saddles 10 and plates 16 the saddles may be accurately placed and sheaves of any ldesired diameter may be fmade, as the diameter is not limited by the necessity of turning the rims, as in the usual practice.

The load carried by each segment or saddle of such a sheave Acanbe accurately calculated and the stresses on the various parts such as spokes, rivets, etc., easily determined and therefore the details of the sheave may be proportioned with condence and economy.

Obviously, sheave wheels constructed as I herein shown and described may be used advantageously with other forms of movable bridges.

Now having described my improvements, what I claim as my invention is 1. In a bridge, the combination of a counterweight, tensional counterweight connections therefor and curved members forming supports for said connections, and said curved members consisting of a plurality of short saddles of a radius less than ythe radius of curvature of said curved members.

2. In a bridge, the combination of acounteriveight, a tensional connection therefor and a plurality of curved supports adapted to support said tensional connection in a curve and each of said supports being of radius less than the radius of said curve and together forming said curve.

3. In a bridge, the combination of a counteriveight, a tensional connection therefor, a curved structure adapted to supportsaid connection, and having its supporting rim composed of short segments of a radius less than'the radius of curvature of said struc-f ture. y

4. In a bridge, the combination of a counterweight, a tensional connection therefor, a

- curved member to support said connection provided with a supporting surface consistingof short saddles, each saddle being of a radius less than the radius of said member, and plates between which said saddles are secured.

Signed at New York city, in the county of New York, and State of New York this 26th day of Ocotober, A. D. 1915.

THOMAS E. BROWN.

Witnesses:

THos. E. BROWN, Jr., CARL T. WESTLIN. 

